title: Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes.
abstract: The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path. For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm for a translation of 39.9 mm. We have demonstrated how interleaved acquired, orthogonal cine-MRI planes can be used for online tracking of soft-tissue target volumes.
authors.affiliation: Department of Applied Mathematics and Computer Science, Technical University of Denmark, Denmark. trbj@dtu.dk
authors.forename: Troels
authors.initials: T
authors.lastname: Bjerre
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Crijns
authors.forename: Per Munck
authors.initials: PM
authors.lastname: af Rosenschöld
authors.forename: Marianne
authors.initials: M
authors.lastname: Aznar
authors.forename: Lena
authors.initials: L
authors.lastname: Specht
authors.forename: Rasmus
authors.initials: R
authors.lastname: Larsen
authors.forename: Paul
authors.initials: P
authors.lastname: Keall
mesh_terms: D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009068:Movement; D061089:Radiotherapy, Image-Guided / Q000379:methods*